#aws #vpc #networking #cidr #ip_address

CIDR is a method for allocation IP addresses, helpful for defining the ip address range Classless inter-domain routing

Format: xxx.zz.yy.kk/32

Components

  • Base ip is: xx.xx.xx.xx, include 4 octets. Example: 192.168.0.0
  • Subnet mask: define how many bits can change in the ip range /32 /26 /24 /16 /8, ….

From CIDR, we can calculate how many ip addresses that we can have based on subnet mask.

Private CIRDs

  • 10.0.x.x big network range
  • 196.168.x.x home network
  • 172.16-31.x.x AWS default VPC

For other CIDR, it’s for public ip addresses.